Hi everybody,

I've been reading http://arrow.apache.org/docs/format/CDataInterface.html, which has been
"... inspired by the Python buffer protocol", and i can't find any details on how to connect this
protocol with other libraries/applications.

Here's what I mean: with the python buffer protocol, i can create a new type and set its
`tp_as_buffer` field to a `PyBufferProcs` structure. This way any other library can call 
`PyObject_CheckBuffer()` on my object to check whether or not it supports the buffer interface,
and then `PyObject_GetBuffer()` to use that interface.

I could not find the corresponding mechanisms in the Arrow C data interface. For example, consider the "Exporting a simple int32 array" tutorial in the article above. After creating 
`export_int32_type()`, `release_int32_type()`, `export_int32_array()`, `release_int32_array()`
-- how do i announce to the world that these functions are available? Conversely, if i want to
talk to an Arrow Table via this interface -- where do i find the endpoints that return 
`ArrowSchema` and `ArrowArray` structures?

(I understand that there is an additional, more complicated API for accessing arrow objects http://arrow.apache.org/docs/python/extending.html, but this seems to be a completely different
API than what CDataInterface describes).